The creation and maintenance of paved surfaces has a long history, but very little in that long history has prepared the industry for its current demands and constraints. Environmental protection pressures have eliminated many otherwise tried-and-true materials and solvents for use as pavement constituents. At the same time, roads and other paved surfaces are experiencing the stresses of greater traffic and larger, heavier vehicles (not to mention additional modern stresses such as acid rain and the extra wear inevitable from aggressive snow and ice removal) and the paving industry must therefore meet commensurately higher paving quality specifications with new, environmentally acceptable materials--and still do so in a commercially competitive way.
One way to preserve the integrity of paved surfaces is to maintain them, so as to avoid the necessity of rebuilding or resurfacing them. A bituminous pavement rejuvenator for such a purpose is disclosed in U.S. Pat. No. 3,221,615, incorporated herein by reference, which is a coal tar derivative composition containing specific ingredients and having particular specifications. Other pavement treating compositions are disclosed in U.S. Pat. Nos. 3,261,269 and No. 4,661,378, also incorporated herein by reference, which disclose pavement dressing conditioners which contain the above-described bituminous pavement rejuvenator together with additional ingredients and/or solvents. These pavement treating compositions are generally spread or sprayed onto existing pavement surfaces (not only bituminous surfaces but concrete and other surfaces as well) to preserve and to restore the integrity of the pavement.
Even these pavement preserving and restoring compositions, however, do not meet all the needs of the current pavement maintenance industry. For example, pavement restorers often wish to restore bituminous pavements with a composition which will also retain a top layer of fine aggregate, for additional strength and finish in the restoration. Fine aggregate can be considered to be any natural or manufactured sand with 100% passing a No. 4 sieve and not more than 10% passing a No. 200 sieve. However, existing pavement treating compositions are not good at retaining fine aggregate. Also, existing pavement treating compositions are not noted for their ability reliably to fill cracks in bituminous pavement or to yield long wear in such repairs--nor are the compositions well adapted for pavement treating followed by immediate resistance to the stresses of weather or restored traffic.
Therefore, a need remains for a composition which can be used to maintain--or to repair--pavement, which has all the advantages of prior art conditioners and rejuvenators, but which also holds fine aggregate, provides long lasting pavement crack repair, gives good resistance to weather even soon after application, and allows for prompt restoration of the pavement to its normal use.